Middle you can probably use Black Devil's Mask, 3D Glasses, or a Black Frame Glasses [1] with some card like Dark Pinguicula / Vanberk / Phylla.

For lower there's pirate dagger, well chewed pencil, umbala spirit.

Note that there is no single best gear and you will want several of the different gears for each situation. For example, MVPs that AGI-up will be impossible to hit unless you have a phreeoni carded imperial spear perhaps. Also, there are other factors like being able to use Inspiration (uses up 1% EXP, time consuming to grind the EXP back) and using certain consumables like enrich celermine juice, Inc HP pots, etc.

And yeah, I don't know what server you are playing on or if you're even playing iRO but good luck with obtaining all the gears.

Hmm there isn't a GREAT card for RGs but as mentioned before, dark pinguicula, vanberk, phylla are decent choices. Also you could consider Marduk for silence immunity since a lot of RGs do not have very high int. Nightmare card for sleep immunity is useful sometimes, as are other immunity cards. There could be some really good MVP headgear card for RGs that I can't think of off the top of my head since these cards/gears are normally just for dreaming and not actually having.

I've heard LotD helm needs to be at a very high + to be effective. If you compare the damage and it's not that different from AK helm + some mid + some lower, definitely go with the AK helm for the extra resist.

Just like with the other situations, get both or all if possible. If you want to get the most out of Shield Spell 1, cast it with a Rosa Shield or Cross Shield to get the full SS1 130 ATK and then switch shields (the effect stays). You don't always have the time to do this or might be lazy though so the 120 ATK from Sacred Mission is definitely enough.

Valk is good against MVPs that have really strong elemental (fire, water, etc.) skills. Sacred Mission is good if the MVP breaks shields (or you can swap to it if your Valk shield breaks) and it's a good idea to keep one around just in case. Immune Shield is also good if the MVP uses neutral melee attacks mostly. Stone bucklers are extremely cheap but some people might not realize that they reduce 5% from Large monsters, which might be nice for MVPs since most MVPs are large. There is also a new shield from Malaya that reduces boss damage I believe.

Also keep in mind that if the MVP's mobs are more of a threat than the MVP itself, or if they are even a threat at all, you might want to use a racial reduction shield instead of Alice (like Khalitzburg card, etc.).

There is also the option of ditching the shield completely for more ASPD. You won't get the shield spell 1 bonus though of course so you may have to do comparisons to see what's better, and it depends on the situation too (solo-ing MVPs in an instance or competing against multiple genes / suras).

Nice. Seems that I should have a lot of different gear for different situations, which is expected. I'm getting the sacred mission first and I plan on putting my alice card on it, since I already have the card.

You get more DEF with higher upgrade but I don't know if you will really feel the difference. There is definitely a small difference of course, but it's kind of insignificant compared to the damage increase you get from weapon upgrades.

I would say +7 or +9 is pretty good already, but since you are on an "unlimited budget", might as well go +11 or +12.